Batteries, such as alkaline batteries, are commonly used as electrical energy sources. Generally, a battery contains a negative electrode (anode) and a positive electrode (cathode). The anode contains an active material (e.g., zinc particles) that can be oxidized; and the cathode contains an active material (e.g., manganese dioxide) that can be reduced. The active material of the anode is capable of reducing the active material of the cathode. In order to prevent direct reaction of the active material of the anode and the active material of the cathode, the electrodes are electrically isolated from each other by a separator.
When a battery is used as an electrical energy source in a device, such as a cellular telephone, electrical contact is made to the electrodes, allowing electrons to flow through the device and permitting the respective oxidation and reduction reactions to occur to provide electrical power. An electrolyte in contact with the electrodes contains ions that flow through the separator between the electrodes to maintain charge balance throughout the battery during discharge.